Mass spectrometry refers to an analysis method that separates and detects compounds by different mass-to-charge ratios (m/z) to implement component and structure identification. The mass spectrometry technique has become increasingly prominent in the field of bioanalysis due to its high specificity and sensitivity. Bio-mass spectrometry (Bio-MS) is a mass spectrometry technique applied to analyze biomolecules, which is widely applied in protein and polypeptide researches such as relative molecular mass determination of protein, peptide mapping determination, peptide sequence determination technique, assignment of sulfhydryl and disulfide bond, posttranslational modification of protein, quantitative proteome analysis, protein-protein interaction research, and the like. Moreover, the bio-mass spectrometry is also applied to such fields as polysaccharose structure determination, oligonucleotide and nucleic acid analysis, microorganism identification, medicament research and development and the like.
The mass spectrometry can obtain the mass information of samples, but cannot give more information effectively for different samples having the same mass. For example, it is different to analyze an ionic structure via the mass spectrometry. Currently, ionic structures are generally analyzed through tandem mass spectrometry (tandem MS) and ion mobility spectrometry. The tandem MS applies energy to fragment an ion to be determined, and analyzes the fragment ion to reconstruct the ionic structure, while the ion mobility spectrometry analyzes the collision cross sectional area of the ion to be determined to analyze the ionic structure. The tandem MS usually works under a high vacuum condition (<1 mTorr), while the ion mobility spectrometry works under a high pressure condition (>1 Torr) and has lower resolution (usually lower than 1,000). These methods require a complicated instrument structure and increased vacuum consumption due to the big difference between the working pressures. Meanwhile, experimental control conditions for the ion to be determined are harsh and ion loss is significant since migration movement of the ion between a plurality of vacuum cavities is involved.
In 2012, Fan Yang, Jacob E. Voelkel and David V. Dearden proposed to analyze collision cross sectional areas of ions from analysis of Fourier transform ion cyclotron resonance spectrum line width so as to analyze the ionic structure in “Collision Cross Sectional Areas from Analysis of Fourier Transform Ion Cyclotron Resonance Line Width: A New Method for Characterizing Molecular Structure” (Anal. Chem., 2012, 84 (11), pp 4851-4857). The method increases the pressure inside a Fourier transform ion cyclotron resonance ion trap to decay an image current of a dominant ion for ion-molecule collision. The rate of decay determines the half peak width (full width at half maximum, FWHM) of the spectrum line. The faster the rate of decay in time domain is, the wider the half peak in corresponding frequency domain is. The ion collision area can be calculated by measuring the half peak width, so that the ion collision area may be analyzed through the decay of the image current of the ion, and finally the ionic structure may be obtained.
Moreover, conventional ion mobility spectrometry can obtain the space size information of the samples, i.e. detect the collision cross sectional area (CCS) of the samples, while obtaining the mass of the samples, and then effectively identity various isomers having the same mass. However, the ion mobility spectrometry increases the analysis cost and reduces the analysis efficiency.